<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>04_class与style绑定</title>
    <style>
        .classA {
            color: red;
        }

        .classB {
            background: blue;
        }

        .classC {
            font-size: 20px;
        }
    </style>
</head>
<body>

<!--
1. 理解
  在应用界面中, 某个(些)元素的样式是变化的
  class/style绑定就是专门用来实现动态样式效果的技术
2. class绑定: :class='xxx'
  xxx是字符串
  xxx是对象
  xxx是数组
3. style绑定
  :style="{ color: activeColor, fontSize: fontSize + 'px' }"
  其中activeColor/fontSize是data属性
-->

<div id="demo">
    <h2>1. class绑定: :class='xxx'</h2>
    <p :class="myClass">xxx是字符串</p>
    <p :class="{classA: hasClassA, classB: hasClassB}">xxx是对象</p>
    <p :class="['classA', 'classB']">xxx是数组</p>

    <h2>2. style绑定</h2>
    <p :style="{color:activeColor, fontSize}">:style="{ color: activeColor, fontSize: fontSize + 'px' }"</p>

    <button @click="update">更新</button>

</div>

<script type="text/javascript" src="../vue.js"></script>
<script type="text/javascript">
    new Vue({
        el: '#demo',
        data: {
            myClass: 'classA',
            hasClassA: true,
            hasClassB: false,
            activeColor: 'red',
            fontSize: '20px'
        },

        methods: {
            update() {
                this.myClass = 'classB'
                this.hasClassA = !this.hasClassA
                this.hasClassB = !this.hasClassB
                this.activeColor = 'yellow'
                this.fontSize = '30px'
            }
        }
    })
</script>
</body>
</html>